我正在研究ViewPager Concept。在ViewPager项目单元格中包含两个项目，如ImageView和TextView。
最初，我将下载Blur Image并在ViewPager单元格中显示。完成后，我将分别下载HighResolution图像并在ViewPager单元格中显示。
例如，如果我将ViewPager中的第一个项目视为模糊图像，并且在背景中它正在下载HighResolution图像，那么它必须刷新ViewPager并在相应的视图单元格中显示HighResolution图像。
在滑动两个项目然后返回第一个项目后，该时间显示高分辨率图像。
所以我的问题是没有向左或向右滑动，如果当前视图中发生任何更改，我需要刷新当前视图。
ViewPager活动类：
public class ViewPagerActivity extends Activity {
ViewPager pager;
String[] _blurImageURL;
PagerAdapter _pagerAdapter;
Context _context;
ViewPagerModel vpModel = new ViewPagerModel();
ArrayList<String> lstQueue=new ArrayList<String>();
Handler _handler=new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_pager);
pager = (ViewPager) findViewById(R.id.pagerView);
_context = this;
_blurImageURL = new String[]{
"http://cdn.connollyphoto.nyc/wp-content/uploads/2014/06/cp_seanbell_portrait_002-800x1200.jpg",
"http://static.wixstatic.com/media/e6f301_7d57a9c0ebdf4d438f88633637aaed77.jpg_srz_930_1395_85_22_0.50_1.20_0.00_jpg_srz",
"http://a4.format-assets.com/image/private/s--TmkImGBO--/c_limit,g_center,h_1200,w_65535/a_auto,fl_keep_iptc.progressive,q_95/31336-7293530-portrait-1_jpg2.jpg",
"http://daviddodgephotography.com/wp-content/uploads/2015/03/Donna_12.jpg",
"http://a3.format-assets.com/image/private/s--W9Flct-g--/c_limit,g_center,h_1200,w_65535/a_auto,fl_keep_iptc.progressive,q_95/173355-8951465-Marvin_Portraits-005.jpg",
"http://www.leifnorman.net/wp-content/uploads/2014/10/IMG_6070.jpg",
"https://dwaynefoong.files.wordpress.com/2012/05/amin-fashion-portrait-dwayne-foong-photography.jpg",
"https://m1.behance.net/rendition/modules/117495331/hd/ce856c4a1fb4c09a5ecec05839f6ddc4.jpg",
"http://www.pcimagenetwork.com/perks/Perks%202013.jpg",
};
_pagerAdapter = new ViewPagerAdapter(_context, vpModel, this);
pager.setAdapter(_pagerAdapter);
// Calling Volley Library to Download the Image for each URLi
for (int i = 0; i < _blurImageURL.length; i++) {
String fileName = String.valueOf(i);
fileName=fileName+"_blurImg";
DownloadImages(_blurImageURL[i], fileName, true);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.view_pager, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void updateView() {
_pagerAdapter.notifyDataSetChanged();
}
public void DownloadQueue(String url_in,String fileName_in)
{
if(lstQueue.contains(fileName_in))
{
Log.i("Duplicate_Request=",fileName_in);
}
else{
lstQueue.add(fileName_in);
DownloadImages(url_in,fileName_in,false);
}
}
void DownloadImages(String imageURL_in, final String fileName_in, final boolean isBlur_in) {
ImageRequest imageRequest = new ImageRequest(imageURL_in,
new Response.Listener<Bitmap>() {
@Override
public void onResponse(final Bitmap response) {
try {
Log.v("Response_Received =",fileName_in);
// Saved in SD Card and getting the Path
String imagePath = SavedInSDCard(response,fileName_in);
//updating the Model
if (isBlur_in) {
vpModel.blurImgLocalPath.add(imagePath);
} else {
vpModel.highResolutionImgLocalPath.add(imagePath);
}
//updating the View
_handler.post(new Runnable() {
@Override
public void run () {
updateView();
}
});
} catch (Exception e) {
e.printStackTrace();
}
}
}, 0, 0, null, null);
ApplicationController.getInstance().addToRequestQueue(imageRequest);
}
public String SavedInSDCard(Bitmap bitmap, String fileName_in) {
File dir = new File(ApplicationController.getAppContext()
.getExternalFilesDir("ViewPager_POC") + "/Cache");
// Create the storage directory if it does not exist
if (!dir.exists()) {
dir.mkdirs();
}
File file = new File(dir, fileName_in);
try {
FileOutputStream out = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 70, out);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
String imgPath = dir + "/" + fileName_in;
return imgPath;
}
}
ViewPager适配器类：
public class ViewPagerAdapter extends PagerAdapter {
Context _context;
LayoutInflater inflater;
ViewPagerActivity _vpActivity;
String[] _highResolutionURL = new String[]{
"http://www.monportraitpro.fr/wp-content/uploads/2014/08/Philippe-Vasilescu.jpg",
"http://www.markhicksphotography.com/wp-content/uploads/2012/01/MHP2012_01_04_MHP_DSC0003.jpg",
"http://www.andrew-mason.com/wp-content/uploads/2013/05/portrait-1-3.jpg",
"http://shutterfinger.typepad.com/.a/6a00e551a6244a8833019affd0eb14970d-pi",
"http://www.antonioolmos.com/data/photos/90_1childs_livebooks.jpg",
"http://www.dvdsreleasedates.com/pictures/800/12000/Zachary-Quinto.jpg",
"http://www.glnphotography.com/wp-content/uploads/2013/09/IMG_1347.jpg",
"http://www.dvdsreleasedates.com/pictures/800/12000/Paul-Walker.jpg",
"http://www.antonioolmos.com/data/photos/89_1blairbooks.jpg",
};
ArrayList<String> _blurImgPath;
ArrayList<String> _highResolutionImgPath;
public ViewPagerAdapter(Context context_in, ViewPagerModel vpModel_in, ViewPagerActivity activity_in) {
_context = context_in;
_blurImgPath = vpModel_in.blurImgLocalPath;
_highResolutionImgPath = vpModel_in.highResolutionImgLocalPath;
_vpActivity = activity_in;
}
@Override
public int getCount() {
return _blurImgPath.size();
}
@Override
public void destroyItem(View container, int position, Object object) {
// TODO Auto-generated method stub
((ViewPager) container).removeView((View) object);
}
@Override
public Object instantiateItem(ViewGroup container, final int position) {
// Declare Variables
TextView txtCounter;
final ImageView imgView;
inflater = (LayoutInflater) _context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.view_pager_item, container,
false);
txtCounter = (TextView) itemView.findViewById(R.id.counter);
imgView = (ImageView) itemView.findViewById(R.id.images);
//Setting the values for Image and textview
txtCounter.setText("" + (position + 1));
//Setting the Image
if (position < _highResolutionImgPath.size()) {
//Setting Hi-ResImage
Log.v("HighRes_ImgPath=", "Get Image from Model" );
imgView.setImageBitmap(BitmapFactory.decodeFile(_highResolutionImgPath.get(position)));
} else {
// Generating the request for HighResolution Image
String fileName = String.valueOf(position + 10);
fileName = fileName + "_clearImg";
Log.v("HighRes_ImgPath=", "Sending Request to Queue=" + fileName);
_vpActivity.DownloadQueue(_highResolutionURL[position], fileName);
//Setting the BlurImage
imgView.setImageBitmap(BitmapFactory.decodeFile(_blurImgPath.get(position)));
}
// Add viewpager_item.xml to ViewPager
((ViewPager) container).addView(itemView);
return itemView;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view == ((RelativeLayout) object);
}
}
ViewPager模型：
public class ViewPagerModel {
ArrayList<String> blurImgLocalPath=new ArrayList<String>();
ArrayList<String> highResolutionImgLocalPath=new ArrayList<String>();
}
activity_view_pager.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.poc_viewpager.ViewPagerActivity" >
<android.support.v4.view.ViewPager
android:id="@+id/pagerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
/>
view_pager_item.xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:id="@+id/images"
android:layout_width="match_parent"
android:layout_height="400dp"
android:layout_alignParentLeft="true" />
<TextView
android:id="@+id/counter"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="43dp" />
</RelativeLayout>
答案 0 :(得分：0)
在这种情况下，我会使用Picasso：
例如：
Picasso.with(getActivity())
.load(URL_THUMBNAIL) // thumbnail url goes here
.into(IMAGEVIEW, new Callback() { // Your image view
// On success start loading the full resolution image
@Override
public void onSuccess() {
Picasso.with(getActivity())
.load(FULL_RESOLUTION_URL) // image url goes here
.into(IMAGEVIEW);
}
@Override
public void onError() {
// Manage downloading errors here
}
});
答案 1 :(得分：0)
在后台线程上调用updateView()。 notifyDataSetChanged()无法在后台线程上运行。在UI线程上调用notifyDataSetChanged()方法，它应该可以解决您的问题